The present invention relates generally to automotive engine fuel delivery systems and, in particular, to a fuel pump assembly including a fuel filter outlet to pump inlet isolator.
Automotive fuel systems, such as those utilizing gasoline or diesel fuel, are well known. An automotive fuel system includes a fuel tank disposed within an automobile body for storing fuel for the internal combustion engine. The fuel tank is typically constructed of steel and is connected to an inlet of a fuel pump. The fuel pump is either a centrifugal or a positive displacement type pump that is driven by an electric motor and an outlet of the fuel pump is connected to a fuel delivery system, typically a fuel injection system or a carburetor. The piping connection from the fuel tank to the inlet of the fuel pump typically includes a fuel filter that protects the internal components of the fuel pump from foreign object damage.
Improvements in manufacturing led to the fuel pump and fuel filter being manufactured as part of a fuel delivery module, which is disposed within the fuel tank. These fuel delivery modules are advantageous because the modules may be preassembled and inserted into the fuel tank later in the assembly process. In addition, fuel delivery modules may be constructed of lighter and cheaper materials, such as plastic. The fuel delivery modules typically attach the outlet of the fuel filter directly to the inlet of the fuel pump, which is mounted in the fuel delivery module. The fuel delivery module, in turn, is mounted on a wall of the fuel tank.
Fuel tanks, especially steel fuel tanks, having the fuel pump or a fuel delivery module disposed therein have notoriously had problems with noise, vibration and harshness (NVH). Vibration problems, in particular, are compounded when the fuel filter, in direct contact with the fuel pump and either the walls of the module or the fuel tank, acts as a conduit through which the vibratory energy travels. Prior art fuel systems have attempted to solve these problems, including the use of damping sleeves, damping seals, damping bushings, and other damping elements, among others. Vibration problems, however, continue to plague fuel systems having integral fuel delivery modules disposed within the fuel tank.
Furthermore, recent developments in noise dampening and insulation have resulted in automobile interiors being much quieter than in previous years. As the noise in the automobile interior is reduced, the driver of the vehicle is now aware of more NVH sources, such as vibration from the automobile""s fuel system, that were inaudible in prior art automobiles. The vibration is distracting to the driver and reduces ride comfort, which in turn reduces the automobile quality and overall customer satisfaction with the automobile.
It is a continuing goal in fuel system design to reduce the amount of NVH in the fuel system. It is an object of the invention, therefore, to provide a fuel delivery system that reduces the NVH of prior art fuel systems and does not produce an objectionable amount of noise for the driver of the automobile.
The present invention concerns a fuel filter outlet to pump inlet isolator for use in an automotive fuel system. The fuel system includes a preferably steel fuel tank disposed within an automobile body for storing and providing fuel to the automobile""s internal combustion engine. An aperture in the exterior surface of the fuel tank receives a fuel delivery module.
The fuel delivery module includes a generally tubular, preferably plastic housing. The housing is preferably sized to conform to the aperture in the exterior surface of the fuel tank. The housing performs a variety of functions, including providing a vessel for storing fuel to be used for starting the automobile and providing a pressure vessel for pressurized fuel, after it has left the outlet of the fuel pump, to be stored prior to delivery to the engine. A primary filter having an inlet end and an outlet end extends radially outwardly from the housing. The primary filter functions as the first means for preventing contamination of the automobile""s fuel supply by not allowing solid particles to pass from the interior of the fuel tank to the interior of the housing.
The housing receives a fuel pump having an inlet connection and an outlet connection and is typically driven by an electric motor. A plurality of electrical connections for the fuel pump motor are disposed on an upper surface of the housing for providing electrical power to the fuel pump motor. The outlet of the fuel pump is connected to provide fuel to a fuel injector or a carburetor at the engine. Optionally, a fuel return line is connected to a top portion of the housing for recirculating unused fuel, favorably reducing fuel wastage.
The housing also receives a fuel pump filter, which is preferably a screen filter having an fuel inlet and a fuel outlet. The fuel pump filter preferably screens smaller particles than the primary filter on the exterior of the housing. The fuel pump filter is preferably constructed of plastic or similar material and is located adjacent a lower portion of the fuel pump. The inlet of the fuel pump filter is open to the interior of the housing. The outlet of the fuel pump filter is preferably a portion of pipe that is connected to the inlet of the fuel pump.
An isolator according to the present invention connects the outlet of the fuel pump filter to the fuel pump inlet. The insertion of the isolator as part of the fuel delivery module prevents direct contact between the fuel pump and the fuel pump filter, advantageously limiting transfer of vibratory energy from the fuel pump to the housing. The isolator preferably possesses vibration dampening properties and is preferably a piece of flexible tubing or piping having an inlet end and an outlet end that is sized to carry the fuel volume required by the fuel pump. The inlet end of the isolator is connected to the outlet of the fuel pump filter. The outlet end of the isolator is connected to the inlet of the fuel pump. The present invention advantageously incorporates a step manifold as part of a lower surface of the fuel delivery module in order to create the needed space for the addition of the isolator.
The present invention isolates the fuel pump from the fuel pump filter by inserting an isolator between the pump inlet and the fuel pump filter as part of the fuel delivery module. The positioning of this isolator advantageously reduces the transfer of energy from the fuel pump via vibration and pressure pulsations to both the fuel delivery module and the steel fuel tank.
The present invention has shown the ability to reduce by half the amount of noise emanating from the prior art fuel pump, fuel delivery module, and fuel tank, making the sound subjectively non-existent.
The isolator according to the present invention may be an integral component of the fuel pump filter or a separate component of the fuel delivery module, advantageously providing more manufacturing options for the fuel delivery module. Not only does the isolator of the present invention act as a dampening device but the isolator is also a conduit for the fuel and is thus a integral component of both the fuel system and the fuel delivery module.
The present invention may be advantageously used with fuel delivery modules with or without fuel return lines. Furthermore, the present invention may be advantageously used with several models of fuel tanks, fuel pumps, and fuel delivery modules currently in production where it is desirable to reduce the amount of NVH of the fuel system, all while remaining within the scope of the invention.